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EC 1.17.99.9 Details
show Brenda entryEC number
1.17.99.9
Accepted name
heme a synthase
Reaction
ferroheme o + H2O + 2 acceptor = ferroheme a + 2 reduced acceptor (overall reaction);;(1a) ferroheme o + H2O + acceptor = ferroheme i + reduced acceptor;;(1b) ferroheme i + H2O + acceptor = hydroxyferroheme i + reduced acceptor;;(1c) hydroxyferroheme i = ferroheme a + H2O (spontaneous)
Other name(s)
COX15 (gene name),
ctaA (gene name)
Systematic name
ferroheme o:acceptor C-81-oxidoreductase (heme a-forming)
Comment
Contains a heme b cofactor. The enzyme catalyses the conversion of heme o to heme a by two successive hydroxylations of the methyl group at C-8, using water as the oxygen source. The first hydroxylation forms heme i, the second hydroxylation results in an unstable dihydroxymethyl group, which spontaneously dehydrates, resulting in the formyl group of heme a [2,4]. The electrons produced by the reaction are transferred to a heme b cofactor [6]. However, the electron acceptor that is used to restore the heme b cofactor to its oxidized state is still not known (both a thioredoxin-like protein and menaquinol have been proposed).
History
created 2020
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1 Oxidoreductases
1.1.1 With NAD+ or NADP+ as acceptor
1.1.3.1 created 1961, deleted 1984 1.1.3.25 created 1986, deleted 2005 1.1.3.26 created 1989, deleted 2002 1.1.3.31 created 1992, deleted 2003 1.1.3.32 created 1999, deleted 2002 1.1.3.33 created 1999, deleted 2002 1.1.3.34 created 1999, deleted 2002 1.1.3.35 created 1999, deleted 2002 1.1.3.36 created 1999, deleted 2002
